CN1531134A - Non-aqueous electrolytic solution and lithium secondary battery containing it - Google Patents

Abstract

An electrolyte for a lithium secondary battery includes lithium salts, a non-aqueous organic solvent, and additive compounds. The additive compounds added to the electrolyte of the present invention decompose earlier than the organic solvent to form a conductive polymer layer on the surface of a positive electrode, and prevent decomposition of the organic solvent. Accordingly, the electrolyte inhibits gas generation caused by decomposition of the organic solvent at initial charging, and thus reduces an increase of internal pressure and swelling during high temperature storage, and also improves safety of the battery during overcharge.

Description

Non-aqueous electrolytic solution and lithium secondary battery containing it

Cross References to Related Applications

This application claims priority to Korean Application No. 2003-15749 filed with the Korean Intellectual Property Office on March 13, 2003, the disclosure of which is incorporated herein by reference.

technical field

The present invention relates to a non-aqueous electrolytic solution and a lithium secondary battery containing the same, more particularly, the present invention relates to a non-aqueous lithium secondary battery that prevents battery expansion during high-temperature storage while maintaining the electrochemical performance of the battery and improving battery safety. water electrolyte.

Background technique

Due to the current trend of more compact and lighter portable electronic devices, there is an increasing need to develop high-performance and large-capacity batteries as power sources for portable electronic devices. In particular, extensive research has been conducted and lithium secondary batteries having excellent safety characteristics and improved electrochemical properties have been obtained. Lithium secondary batteries utilize those materials that reversibly intercalate or deintercalate lithium ions during charge and discharge reactions as positive and negative electrode active materials. The positive electrode active material includes lithium metal oxide, and the negative electrode active material includes lithium metal, lithium-containing alloys, or materials capable of inserting or extracting lithium ions such as crystalline carbon or amorphous carbon, or carbon-containing composites.

Figure 1 shows a cross-sectional view of a common non-aqueous lithium-ion battery. A lithium ion battery 1 is prepared by inserting an electrode assembly 8 including a positive electrode 2 , a negative electrode 4 , and a separator 6 between the positive and negative electrodes into a battery case 10 . The electrolytic solution 26 is injected into the battery case 10 and impregnated into the separator 6 . The upper part of the battery case 10 is sealed with a cover plate 12 and a sealing gasket 14 . The cover plate 12 has a safety hole 16 for pressure relief. The positive terminal 18 and the negative terminal 20 are respectively connected to the positive electrode 2 and the negative electrode 4 . Insulators 22 and 24 are installed at the lower and side portions of the electrode assembly 8 to prevent short circuits in the battery.

The average discharge voltage of lithium secondary batteries is about 3.6-3.7V, which is higher than that of other alkaline batteries, Ni-MH batteries, Ni-Cd batteries, and the like. In order to generate the required high driving voltage, the electrolyte must be electrochemically stable in the charge-discharge voltage range of 0-4.2V. Therefore, a mixture of nonaqueous carbonate-based solvents such as ethylene carbonate, dimethyl carbonate, and diethyl carbonate is used as the electrolytic solution. However, the ionic conductivity of this electrolyte is much lower than that of aqueous electrolytes used in Ni-MH batteries or Ni-Cd batteries, leading to deterioration of battery characteristics during high-speed charge and discharge.

During the initial charge of a lithium secondary battery, lithium ions are released from the battery's lithium-transition metal oxide positive electrode and transferred to the carbon negative electrode, where they are intercalated in carbon. Due to the high reactivity of lithium, lithium reacts with the carbon negative electrode to generate Li ₂ CO ₃ , LiO, LiOH, etc., and then forms a thin film on the surface of the negative electrode. This thin film is called an organic solid electrolyte interface (SEI) thin film. The organic SEI film formed during initial charging not only prevents the reaction of lithium ions with carbon anodes or other materials during charge and discharge, but also acts as an ion channel, allowing only lithium ions to pass through. This ion channel prevents the disintegration of the carbon anode structure caused by the co-intercalation of high molecular weight solvents and solvated lithium ions into the carbon anode.

Once the organic SEI film is formed, lithium ions no longer react with carbon electrodes or other materials, so that the amount of lithium ions is maintained. That is to say, the carbon of the negative electrode reacts with the electrolyte during the initial charge, thereby forming a passivation layer such as an organic SEI film on the surface of the negative electrode, so that the electrolyte is no longer decomposed, and stable charge and discharge can be maintained (J. Power Sources, 51 (1994), 79-104). Therefore, in the lithium secondary battery, there is no irreversible formation reaction of the passivation layer, and a stable cycle life can be maintained after the initial charging reaction.

However, gas is generated inside the battery due to the decomposition of the carbonate-based organic solvent during the formation reaction of the organic SEI film (J. Power Sources, 72 (1998), 66-70). The gas includes H ₂ , CO, CO ₂ , CH ₄ , C ₂ H ₆ , C ₃ H ₈ , C ₃ H ₆ , etc., depending on the type of non-aqueous organic solvent and negative active material used. The thickness of the battery increases during charging due to gas generation inside the battery, and the passivation layer slowly decomposes due to electrochemical energy and thermal energy, and this decomposition increases with time when the battery is stored at high temperature after charging. Therefore, side reactions continue to occur in which the exposed negative electrode surface reacts with the surrounding electrolyte.

The above-mentioned problems also occur in the positive electrode. During the initial charge, the positive electrode active material reacts with the electrolyte to form a passivation layer on the positive electrode, which prevents the decomposition of the electrolyte, thus maintaining stable charge and discharge. As in the negative electrode, the charge consumed in forming the passivation layer on the positive electrode is irreversible. Thus, in the lithium ion battery, there is no irreversible formation reaction of the passivation layer, and a stable cycle life can be maintained after the initial charging reaction.

However, the passivation layer slowly decomposes due to electrochemical and thermal energy, and this decomposition increases over time when the battery is stored at high temperature after being fully charged, for example, charging the battery 100% at 4.2V, Then storage at 85°C for 4 days will do the trick. Therefore, a side reaction in which the exposed positive electrode surface reacts with the surrounding electrolyte and generates gas continues to occur. The gases produced include CO, CO ₂ , CH ₄ , C ₂ H ₆ , etc. from the decomposition of carbonate-based solvolysis.

The internal pressure of the battery increases as gas is generated in the positive and negative electrodes. An increase in internal pressure induces deformation of a prismatic Li-polymer battery. As a result, a regional difference in cohesion occurs between the electrodes in the battery electrode assembly (positive and negative electrodes and separators), thereby deteriorating the performance and safety of the battery, and causing lithium secondary batteries to be installed in electronic equipment difficult to install.

In addition, the decomposition of the passivation layer due to the increase of electrical energy or thermal energy also causes continuous side reactions between the positive and negative electrodes and the electrodes. The gas generated by the side reaction increases the pressure inside the battery and causes deformation of the battery, which in turn causes short circuit and thermal runaway.

In order to solve the internal pressure problem, one method of improving the safety of a secondary battery containing a nonaqueous electrolyte is to install a vent or a cutout to discharge the internal electrolyte when the internal pressure rises to a predetermined level. However, this method has a problem in that mis-operation may originate from an increase in internal pressure itself.

Also, a method of suppressing an increase in internal pressure by injecting an additive into an electrolytic solution to change the SEI formation reaction is also known. For example, Japanese Patent Laid-Open No. 97-73918 discloses a method in which high-temperature storage characteristics of a battery are improved by adding 1% or less of a diphenylpicrylhydrazine compound to an electrolytic solution. Japanese Patent Laid-Open No. 96-321312 discloses a method in which 1-20% of N-butylamine-based compound is used in the electrolyte to improve cycle life and long-term storage characteristics. Japanese Patent Laid-Open No. 96-64238 discloses a method in which storage characteristics of a battery are improved by adding 3×10 ⁻⁴ to 3×10 ⁻³ M of a calcium salt to an electrolytic solution. Japanese Patent Laid-Open No. 94-333596 discloses a method in which the reaction between the electrolyte solution and the negative electrode of the battery is suppressed by adding an azo compound, thereby improving the storage characteristics of the battery. In addition, Japanese Patent Laid-Open No. 95-320779 discloses a method in which CO ₂ is added to the electrolytic solution, and Japanese Patent Laid-Open No. 95-320779 also discloses that a sulfide-based compound is added to the electrolytic solution to prevent the electrolytic solution from decomposing. method.

The above method induces the formation of a suitable film such as an organic SEI film on the surface of the negative electrode by adding a small amount of organic or inorganic materials, thereby improving the storage characteristics and safety of the battery. However, the above-mentioned methods suffer from various problems: due to their inherent electrochemical properties, the added compounds decompose or form unstable films during the initial charge-discharge period by interacting with the carbon anode, resulting in the deterioration of ion mobility in the electrolyte; And gas is generated inside the battery, which increases the internal pressure and significantly deteriorates the storage, safety, cycle life and capacity characteristics of the battery.

Contents of the invention

In one aspect, the present invention provides a non-aqueous electrolytic solution for a lithium secondary battery including an additive compound for suppressing gas generation inside the battery when it is stored at a high temperature after charging.

In another aspect, the present invention provides a non-aqueous electrolyte solution for a lithium secondary battery, which improves safety by suppressing overcharge.

In yet another aspect, the present invention provides a lithium secondary battery having effective high-temperature storage characteristics and good safety.

In order to achieve these aspects, the present invention provides a kind of electrolytic solution of lithium secondary battery, and this electrolytic solution comprises lithium salt; Non-aqueous organic solvent; And at least one additive selected from the compound shown in following formula (1) to (6) Compound:

wherein R ₁ and R ₂ are independently selected from hydroxyl, C ₁ -C ₆ alkoxy, C ₂ -C ₆ alkenyl, halogen substituted C ₁ -C ₆ alkoxy, C ₁ -C ₄ alkyl, C ₂ ~C ₄ alkenyl, C ₆ ~C ₁₄ aryl, C ₃ ~C ₆ cycloalkyl, halogen substituted alkyl, alkenyl, aryl, cycloalkyl and halogen substituted C ₂ ~C ₆ alkenyl; and R ₃ and R ₄ are independently selected from C ₁ ~C ₆ alkyl, C ₆ ~C ₁₂ aryl, and methyl;

wherein Y ₁ is selected from O, NR (wherein R is hydrogen, C ₁ ~C ₆ alkyl, C ₆ ~C ₁₂ aryl, preferably 1-phenylsulfonyl), and S; and R ₅ and R ₆ are independently selected from hydrogen, C ₁ ~C ₆ alkyl, C ₁ ~C ₆ alkoxy, C ₂ ~C ₆ alkenyl, C ₆ ~C ₁₂ aryl, and acetyl, and preferably methyl;

wherein Y ₂ is selected from O, N, and S; and R ₇ is selected from hydrogen, C ₁ ~C ₆ alkyl, C ₁ ~C ₆ alkoxy, C ₂ ~C ₆ alkenyl, and C ₆ ~C ₁₂ aryl;

wherein X _{and X} are independently selected from hydrogen and a halogen selected from F, Cl, and Br, and preferably Cl or Br;

wherein X _{and X} are independently selected from hydrogen and a halogen selected from F, Cl, and Br, and preferably Cl or Br; and

wherein Y ₃ is selected from N, O, and S, and preferably N; Y ₄ is NR' (where R' is hydrogen or C ₁ -C ₆ alkyl), O, S, or preferably NH; and R ₈ is selected from Hydrogen, C ₁ -C ₆ alkyl, C ₁ -C ₆ alkoxy, C ₂ -C ₆ alkenyl, C ₆ -C ₁₂ aryl, and acetyl.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

The present invention also provides a lithium secondary battery containing the electrolytic solution.

Description of drawings

These and/or other aspects and advantages of the present invention will be apparent and more readily understood from the following description of preferred embodiments when taken in conjunction with the accompanying drawings.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention, in which:

Fig. 1 is a sectional view of a prismatic lithium secondary battery;

Fig. 2 shows the result of utilizing LSV (Linear Sweep Voltammetry) to measure the decomposition initiation voltage of the electrolyte of Example 4 of the present invention and Comparative Example 1;

Fig. 3 is a graph of thickness changes measured every 24 hours after batteries containing the electrolytes of Examples 1-5 and Comparative Example 1 were placed in a room at 85°C for 4 days;

Fig. 4 is a graph of thickness changes measured every 24 hours after batteries containing the electrolytes of Examples 6-8 and Comparative Example 1 were placed in a room at 85°C for 4 days;

Fig. 5 is a graph of thickness changes measured every 24 hours after batteries containing the electrolytes of Examples 15-18 and Comparative Example 1 were placed in a room at 85°C for 4 days;

Fig. 6 is a graph of thickness changes measured every 24 hours after batteries containing the electrolyte solutions of Examples 19-26 and Comparative Example 1 were placed in a room at 85°C for 4 days;

Fig. 7 is a graph of thickness changes measured every 24 hours after batteries containing the electrolytes of Examples 4, 7 and 16 and Comparative Example 1 were placed in a room at 80° C. for 10 days; and

Fig. 8 is a graph showing the battery temperature when the batteries of Examples 5, 8, 10 and 17 of the present invention and Comparative Example 1 are overcharged at 1C to a voltage of 12V for 2 hours.

Detailed ways

The preferred embodiments of the invention will now be described in detail, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

In the following detailed description, selected embodiments of the invention are shown and described merely by simply setting forth the best mode contemplated by the inventors for carrying out the invention. It should be understood that changes may be made in various aspects of the invention, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive.

The electrolytic solution of the present invention is prepared by adding at least one additive compound having the following formulas (1) to (6) to a non-aqueous solvent containing a lithium salt:

wherein R ₁ and R ₂ are independently selected from hydroxyl, C ₁ ~C ₆ alkoxy, C ₂ ~C ₆ alkenyl, halogen substituted C ₁ ~C ₆ alkoxy, and halogen substituted C ₂ ~C ₆ alkenyl, and preferably hydroxyl; and R ₃ and R ₄ are independently selected from C ₁ ~ C ₆ alkyl and C ₆ ~ C ₁₂ aryl, and preferably methyl;

wherein Y ₁ is selected from O, NR (where R is hydrogen, C ₁ ~C ₆ alkyl, C ₆ ~C ₁₂ aryl, or preferably 1-phenylsulfonyl), and S; and R ₅ and R ₆ are independent is selected from hydrogen, C ₁ ~C ₆ alkyl, C ₁ ~C ₆ alkoxy, C ₂ ~C ₆ alkenyl, C ₆ ~C ₁₂ aryl, and acetyl, and preferably methyl;

wherein Y ₂ is selected from O, N, and S; and R ₇ is selected from hydrogen, C ₁ ~C ₆ alkyl, C ₁ ~C ₆ alkoxy, C ₂ ~C ₆ alkenyl, and C ₆ ~C ₁₂ aryl;

Wherein X _{and X} are independently selected from hydrogen and selected from F, Cl, and a halogen of Br, preferably Cl or Br;

wherein X _{and X} are independently selected from hydrogen and a halogen selected from F, Cl, and Br, preferably Cl or Br; and

wherein Y ₃ is selected from N, O, and S, preferably N; Y ₄ is NR' (wherein R' is hydrogen or C ₁ ~C ₆ alkyl), O, S, or preferably NH; and R ₈ is selected from hydrogen , C ₁ -C ₆ alkyl, C ₁ -C ₆ alkoxy, C ₂ -C ₆ alkenyl, C ₆ -C ₁₂ aryl, and acetyl.

Generally, in order to prevent the internal pressure from increasing due to gas generation, a method of forming an SEI layer to prevent side reactions between the anode and the electrolyte has been developed.

At a high temperature, decomposition of the electrolytic solution on the surface of the positive electrode actively occurs, which leads to an increase in the internal pressure of the battery. Therefore, the present invention uses an additive compound to form a passivation layer on the surface of the positive electrode, thereby preventing oxidative decomposition of the electrolyte. During the initial charging process, the additive compound is decomposed before the organic solvent of the electrolyte, resulting in the formation of a passivation layer on the surface of the positive electrode, thereby inhibiting the decomposition of the organic solvent of the electrolyte. Swelling during storage at high temperature after the battery is fully charged is also suppressed because gas generation due to decomposition of the organic solvent of the electrolytic solution during initial charging is suppressed. In addition, there is also no deterioration in low temperature and storage characteristics and charge and discharge capacity of the lithium secondary battery. Suppresses the expansion of the battery when it is stored at high temperature after being fully charged, and improves the reliability of the battery after the battery pack is installed.

The additive compound of the present invention starts to decompose when the voltage of the battery reaches the overcharge voltage, and undergoes electrochemical polymerization, resulting in the formation of a conductive polymer layer on the surface of the positive electrode. The conductive polymer layer effectively acts as a resist and overcharge inhibitor since the layer is difficult to redissolve. Additive compounds reduce heat release, prevent heat escape, and improve safety.

Currently used positive electrode active materials include lithium-cobalt-based oxides, lithium-manganese-based oxides, lithium-nickel-based oxides, lithium-nickel-manganese-based oxides, and the like. Lithium-nickel-based or lithium-nickel-manganese-based oxides are inexpensive and offer high discharge capacity, but are limited by gas generation during high-temperature storage. To solve this problem, improved negative active materials have been developed. The electrolyte solution containing additives of the present invention solves the above problems, even if conventional lithium-nickel-based or lithium-nickel-manganese-based oxides are used as positive electrode active materials, and conventional carbonaceous materials are used as negative electrode active materials.

As shown in Table 1, additive compounds include bisphenol A, 2,5-dimethylfuran, 2-acetylfuran, 2-acetyl-5-methylfuran, 1-(phenylsulfonyl)pyrrole, 2 , 3-benzofuran, 2-butylbenzofuran, thioindenne, 2,3-dichloro-1,4-naphthoquinone, 1,2-naphthoquinone, 2,3-dibromo-1,4- Naphthoquinone, 3-bromo-1,2-naphthoquinone, 2-methylimidazole, etc. Preference is given to bisphenol A, 2,5-dimethylfuran, 2-butylbenzofuran, thioinden, and 2,3-dichloro-1,4-naphthoquinone.

Table 1

The additive compound is basically added in an amount of 0.01-10%, preferably 0.01-5%, more preferably 0.01-1%, even more preferably 0.01-0.5% of the total weight of the electrolyte. When the compound is used in an amount of less than 0.01% by weight, it is unlikely to have an effect of suppressing gas generation inside the battery. When the compound is used in an amount exceeding 10% by weight, battery performance such as cycle life characteristics deteriorates because the formation of a thick conductive layer lowers the reversibility of the battery.

Preferred lithium salts are selected from LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl _4. At least one of LiN(C _x F _2x+1 SO ₂ )(C _y F _2y+1 SO ₂ ) (where x and y are natural numbers), LiCl, and LiI.

The concentration of the lithium salt is preferably 0.6 to 2.0M. When the concentration of lithium salt is less than 0.6M, the electrolyte performance deteriorates due to its lack of ionic conductivity. When the concentration of the lithium salt is greater than 2.0M, the mobility of lithium ions decreases due to the increase in the viscosity of the electrolyte, and the low-temperature performance also decreases.

The lithium salt acts as a supply source of lithium ions in the battery, enabling the basic operation of the lithium secondary battery. The non-aqueous organic solvent functions as a medium in which ions capable of participating in electrochemical reactions can migrate.

Non-aqueous organic solvents may include carbonates, esters, ethers, or ketones. Examples of carbonates include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), ethylmethyl carbonate ( MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). Examples of esters include γ-butyrolactone (γ-BL), methyl acetate, ethyl acetate, n-propyl acetate and the like. Examples of ethers include dibutyl ether and the like. However, the non-aqueous organic solvent is not limited to the above solvents.

Preference is given to using mixtures of chain carbonates and cyclic carbonates. Preferably, the volume mixing ratio of cyclic carbonates and chain carbonates is 1:1 to 1:9. When the cyclic carbonate and the chain carbonate are mixed in a volume ratio of 1:1˜1:9, and the mixture is used as the electrolyte, the performance of the electrolyte can be enhanced.

In addition, the electrolytic solution of the present invention can also comprise the mixture of carbonate solvent and the aromatic hydrocarbon solvent of following formula (7):

Wherein R ₉ is halogen or C ₁ -C ₁₀ alkyl, and n is an integer of 1-6.

Examples of aromatic hydrocarbon solvents include benzene, chlorobenzene, nitrobenzene, fluorobenzene, toluene, trifluorotoluene, and xylene.

Preferably, the carbonate solvent and the aromatic hydrocarbon solvent are mixed together in a volume ratio of 1:1 to 30:1. When the carbonate solvent and the aromatic hydrocarbon solvent are mixed with each other in the above volume ratio, and the mixture is used as the electrolyte, the performance of the electrolyte can be enhanced.

According to another embodiment of the present invention, the organic sulfone-based compound of the following formula (8) can be added to the electrolytic solution together with the additive compounds of the formulas (1) to (6):

Wherein R ₁₀ and R ₁₁ are independently selected from primary, secondary or tertiary alkyl, alkenyl, cycloalkyl and aryl, and preferably C ₁ ~ C ₄ alkyl, C ₂ ~ C ₄ alkenyl, C ₃ ~C ₆ cycloalkyl or C ₆ ~C ₁₄ aryl, or R ₁₀ and R ₁₁ combine to form a ring. More preferably, one of R ₁₀ and R ₁₁ is a halogen-substituted alkyl, alkenyl, aryl or cycloalkyl, and either one of R ₁₀ or R ₁₁ is an alkenyl such as vinyl. Organic sulfone-based compounds suppress gas generation on electrodes at high temperatures, and improve cycle life and capacity characteristics. The sulfone-based compound is basically added to the non-aqueous solvent in an amount of 0.01-5%, preferably 0.01-1%, of the total weight of the electrolyte.

The electrolyte solution of the lithium secondary battery of the present invention is stable in the temperature range of -20 to 60° C., and thus can maintain stable battery characteristics even at a voltage of 4V. The electrolyte solution of the present invention can be applied to all lithium secondary batteries such as lithium ion batteries, lithium polymer batteries and the like.

The invention provides a lithium battery containing the electrolyte. The lithium battery of the present invention uses a material that reversibly intercalates/extracts lithium ions (lithium oxide intercalation compound), or a material that reversibly forms a lithium-containing compound as a positive electrode active material. Examples of materials that reversibly intercalate/extract lithium ions are lithium-containing metal oxides or lithium-containing chalcogenides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , and LiNi _1-xy Co _x M _y O ₂ (0≤x≤1, 0≤y≤1, 0≤x+y≤1, M is a metal such as Al, Sr, Mg, La, etc.).

The lithium secondary battery of the present invention uses lithium metal, a lithium-containing alloy, or a material that reversibly intercalates/extracts lithium ions as the negative electrode active material. Examples of materials that reversibly intercalate/extract lithium ions are crystalline carbon or amorphous carbon or carbon composites.

A lithium secondary battery was prepared by the following method. The positive and negative electrodes are prepared by coating a slurry containing the active material on a current collector of suitable thickness and length. An electrode assembly is prepared by winding or laminating a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode, and then the electrode assembly is placed in a battery case. The electrolyte solution of the present invention is injected into the battery case, and then the upper part of the battery case is sealed. The separator between the positive and negative electrodes can be a single-layer separator of polyethylene, polypropylene or polyvinylidene fluoride; a double-layer separator of polyethylene/polypropylene; a three-layer separator of polyethylene/polypropylene/polyethylene board; or polypropylene/polyethylene/polypropylene three-layer separator.

The present invention will now be further explained in more detail with reference to the following examples. However, these examples should not be construed as limiting the scope of the present invention in any sense.

Examples and comparative examples

Examples 1-26

Ethylene carbonate/ethyl methyl carbonate (EC/EMC) was mixed at a volume ratio of 1:1 to prepare a non-aqueous organic solvent. 1M LiPF ₆ was added to the solvent, and the additive compounds shown in Table 2 were further added basically in the amount shown in Table 2 (based on the total weight of the electrolyte) to prepare the electrolyte.

Table 2 Electrolyte additive compound Amount of compound (weight %) Example 1 Bisphenol A 0.25 Example 2 Bisphenol A 0.5 Example 3 Bisphenol A 0.75 Example 4 Bisphenol A 1.0 Example 5 Bisphenol A 2.0 Example 6 2,5-Dimethylfuran 0.5 Example 7 2,5-Dimethylfuran 1.0 Example 8 2,5-Dimethylfuran 3.0 Example 9 2-Butylbenzofuran 0.5 Example 10 2-Butylbenzofuran 1.0 Example 11 2-Butylbenzofuran 3.0 Example 12 Thiainthene 0.5 Example 13 Thiainthene 1.0 Example 14 Thiainthene 3.0 Example 15 2,3-Dichloro-1,4-naphthoquinone 0.5 Example 16 2,3-Dichloro-1,4-naphthoquinone 1.0 Example 17 2,3-Dichloro-1,4-naphthoquinone 3.0 Example 18 2,3-Dichloro-1,4-naphthoquinone 5.0 Example 19 1,2-Naphthoquinone 0.5 Example 20 2,3-Dibromo-1,4-naphthoquinone 0.5 Example 21 3-bromo-1,2-naphthoquinone 0.5 Example 22 2-Acetylfuran 0.5 Example 23 2-Acetyl-5-methylfuran 0.5 Example 24 2-Methylimidazole 0.5 Example 25 1-(Phenylsulfonyl)pyrrole 0.5 Example 26 2,3-Benzofuran 0.5

Comparative example 1

1M _LiPF6 was added to a non-aqueous organic solvent of ethylene carbonate/ethyl methyl carbonate (EC/EMC) mixed at a volume ratio of 1:1 to prepare a non-aqueous electrolyte.

Measure the voltage at which decomposition begins

The decomposition onset voltages of the electrolytic solutions according to Examples 2, 6, 9, 12, 15, 19, 20-26, and Comparative Example 1 were measured by LSV (Linear Sweep Voltammetry). Decomposition start voltage is shown in Table 3

table 3 Electrolyte additive compound Decomposition start voltage (V) Example 2 Bisphenol A 4.40 Example 6 2,5-Dimethylfuran 4.10 Example 9 2-Butylbenzofuran 4.34 Example 12 Thiainthene 4.26 Example 15 2,3-Dichloro-1,4-naphthoquinone 5.00 Example 19 1,2-Naphthoquinone 5.05 Example 20 2,3-Dibromo-1,4-naphthoquinone 5.05 Example 21 3-bromo-1,2-naphthoquinone 5.00 Example 22 2-Acetylfuran 4.96 Example 23 2-Acetyl-5-methylfuran 4.63 Example 24 2-Methylimidazole 4.57 Example 25 1-(Phenylsulfonyl)pyrrole 4.68 Example 26 2,3-Benzofuran 4.43 Comparative example 1 no additive compound 5.70

The sub-conditions for the decomposition onset voltage are as follows:

Working electrode: Pt; reference electrode: Li-metal; counter electrode: Li-metal; voltage range: 3-7V; scanning speed: 5mV/s.

As shown in Table 3, the decomposition onset voltage of the electrolytic solution of the example is lower than that of the electrolytic solution of the comparative example 1. Therefore, the electrolyte solution of the embodiment first decomposes during the initial charge, and forms a conductive polymer layer on the positive electrode above the decomposition initiation voltage.

FIG. 2 shows the results of measuring the decomposition onset voltages of the electrolytes of Example 4 and Comparative Example 1 by LSV (Linear Sweep Voltammetry). As shown in FIG. 2 , the electrolyte solution of Example 4 has a decomposition initiation voltage of 4.4V, while that of Comparative Example 1 is 5.7V. The electrolytic solution of Example 4 to which bisphenol A was added had a lower decomposition initiation voltage than the electrolytic solution of Comparative Example 1 to which bisphenol A was not added. Therefore, the electrolyte solution of Example 4 first decomposes during the initial charge and forms a conductive polymer layer on the positive electrode. The conductive polymer layer prevents the decomposition of carbonate-based organic solvents and the resulting gas generation, thereby reducing the internal pressure of the battery and increasing its thickness after full charge. In the LSV curve of Example 4 shown in Figure 2, it is assumed that the 4.5-5V region represented by (1) represents the maintenance of the established current, indicating that the reaction to form a passivation layer has taken place; and the 6.5V region represented by (2) The -7V region represents the maintenance of the established current, which is beneficial for battery safety.

Preparation of lithium secondary battery

After LiCoO ₂ (as the positive electrode active material), polyvinylidene fluoride (PVdF) (as the binder), and acetylene black (as the conductive agent) were mixed in a weight ratio of 92:4:4, the mixture was The cathode active material slurry was prepared by dispersing in N-methyl-2-pyrrolidone (NMP). This slurry was coated on a 20 μm thick aluminum foil, dried, and pressed, whereby a positive electrode was produced. After the crystalline artificial graphite as a negative active material and PVdF as a binder were mixed in a weight ratio of 92:8, a negative active material slurry was prepared by dispersing the mixture in NMP. This slurry was coated on a 15 μm thick copper foil, dried, and pressed, whereby a negative electrode was produced. Together with a 25 μm thick polyethylene separator, the as-prepared electrodes were coiled and pressed, and then placed in a prismatic container with dimensions of 30 mm × 48 mm × 6 mm in height. The electrolyte solutions of Examples 1-26 and Comparative Example 1 were injected into the container, thus completing the preparation of the prismatic lithium ion battery.

The increase rate of battery thickness after charging and the life characteristics of mixed ring

Under constant current and constant voltage (CC-CV) conditions, the lithium battery prepared by injecting the electrolyte of Examples 1 to 26 and Comparative Example 1 was charged to a cut-off voltage of 4.2V with a current of 166mA, and allowed to stand 1 hour, then discharge to a cut-off voltage of 2.75V with a current of 166mA, and let it stand for 1 hour. After 3 charge/discharge cycles, the battery was fully charged to a cut-off voltage of 4.2V within 3 hours at a current of 415mA. They were left in a high temperature chamber (85° C.) for 4 days. The thickness of each battery was measured every 24 hours after charging, and the battery thickness increase rate (relative to the thickness measured after the battery was fabricated) was calculated. The measurement results of Examples 1-26 and Comparative Example 1 are shown in Table 4 and FIGS. 3-6. Examples 1-5, Examples 6-8, Examples 15-18, and Examples 19-26 are shown in Figures 3, 4, 5, and 6, respectively. The thickness data in Table 4 and FIGS. 3 to 6 are average values of 10 test cells. For ease of comparison, the results of Comparative Example 1 are also shown.

The lithium-ion batteries prepared with the electrolytes of Examples 1-26 and Comparative Example 1 were charged to a cut-off voltage of 4.2V at 1C under CC-CV conditions, and discharged to a cut-off voltage of 3.0V at 1C under CC-CV Voltage. The battery was subjected to 300 cycles of charge and discharge, and the cycle life characteristics (capacity retention rate) of the battery were measured. Table 4 shows the results related to Examples 1 to 26 and Comparative Example 1. The capacity retention data in Table 4 are the average values of 10 test batteries.

Table 4 Thickness increase rate after leaving the battery standing for 4 days Capacity retention after 100 cycles Capacity retention after 300 cycles Example 1 10% 97% 90% Example 2 11% 96% 89% Example 3 9% 95% 88% Example 4 9% 93% 87% Example 5 12% 91% 85% Example 6 10% 97% 87% Example 7 10% 94% 88% Example 8 12% 95% 86% Example 9 12% 98% 85% Example 10 10% 97% 88% Example 11 9% 96% 89% Example 12 15% 98% 87% Example 13 12% 97% 88% Example 14 13% 96% 85% Example 15 10% 95% 84% Example 16 12% 93% 87% Example 17 11% 94% 86% Example 18 13% 92% 84% Example 19 7% 94% 83% Example 20 15% 95% 84% Example 21 16% 97% 84% Example 22 16% 97% 83% Example 23 14% 95% 85% Example 24 12% 96% 83% Example 25 14% 96% 85% Example 26 9% 93% 84% Comparative example 1 30% 90% 80%

As shown in Table 4 and FIGS. 3 to 6 , the thickness increase of the lithium ion battery into which the electrolyte solution of the example was injected was substantially smaller than that of the lithium ion battery into which the electrolyte solution of Comparative Example 1 was injected. Table 4 shows that the capacity retention rate of the batteries comprising the electrolytes of Examples 1 to 26 after 100 and 300 cycles is much greater than that of Comparative Example 1, indicating that the batteries comprising the electrolytes of Examples 1 to 26 have effective cycle life characteristics.

FIG. 7 shows the thickness change of lithium-ion batteries injected with the electrolyte solutions of Examples 4, 7, and 16 and Comparative Example 1 after being placed in a high-temperature room (80° C.) for 10 days. As shown in FIG. 7 , the batteries including the electrolyte solutions of Examples 4, 7, and 16 had significantly lower thickness increase rates than those of Comparative Example 1, even after being left at a high temperature for a long time.

FIG. 8 shows the surface temperature of lithium-ion batteries containing the electrolytes of Examples 5, 8, 10, and 17 and Comparative Example 1 when overcharged at 1C for 2 hours at a voltage of 12V. As shown in FIG. 8, the cells of Examples 5, 8, 10, and 17 had negligible temperature rise after charging for about 40 minutes because the heat release was reduced by adding additive compounds to the electrolyte. Therefore, the additive compound acts as an inhibitor of thermal runaway during overcharging, thereby improving safety. In contrast, the temperature of the battery of Comparative Example 1 suddenly increased to 140° C. after 40 minutes of overcharging.

With respect to 10 test batteries comprising the electrolyte solutions of Examples 4, 7, 11, 14, 17, and 19, and Comparative Example 1, their safety when exposed to heat was evaluated. Each battery was heated at 150° C. for 1 hour, and the condition of each battery was evaluated. The results are shown in Table 5.

table 5 Safety when exposed to heat ^* Example 4 9L0, 1L1 Example 7 10L0 Example 11 10L0 Example 14 10L0 Example 17 9L0, 1L1 Example 19 8L0, 2L1 Comparative example 1 5L4, 5L5

^* The number in front of "L" indicates the number of batteries tested

The safety results were graded as follows:

L0: Good, L1: Leakage, L2: Flash, L2: Flame, L3: Smoke, L4: Ignition, L5: Explosion.

As shown in Table 5, the battery of Example has good safety characteristics, for example, when subjected to overcharge and heat, and also has more desirable high-temperature storage characteristics and cycle life compared with Comparative Example 1.

The additive compound added to the electrolytic solution of the present invention decomposes earlier than the organic solvent alone to form a conductive polymer layer on the surface of the positive electrode and prevent the decomposition of the organic solvent. Therefore, the electrolytic solution of the present invention suppresses gas generation due to decomposition of organic solvents at initial charging, thereby reducing internal pressure increase and expansion at high temperature storage, and improving battery safety at overcharging.

The foregoing is merely illustrative of the principles of the invention. Furthermore, since various modifications and changes will readily occur to those skilled in the art, it is not intended that the invention be limited to that shown and described. Accordingly, all suitable modifications and equivalents which may be utilized fall within the scope of the invention and the appended claims.

Although some preferred embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that changes may be made to the embodiments without departing from the spirit and scope of the present invention, which is defined as in the claims and their equivalents.

Claims (48)

1. the nonaqueous electrolytic solution of a lithium secondary battery comprises:

Lithium salts;

Organic solvent; And

At least a additive compound, it is selected from the compound shown in the following formula (1) to (6):

R wherein ₁And R ₂Be independently selected from hydroxyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, the C that halogen replaces ₁～C ₆The C that alkoxyl and halogen replace ₂～C ₆Alkenyl; And R ₃And R ₄Be independently selected from C ₁～C ₆Alkyl, C ₆～C ₁₂Aryl, and methyl;

Y wherein ₁Be selected from O, NR and S wherein R are selected from hydrogen, C ₁～C ₆Alkyl, C ₆～C ₁₂Aryl, and 1-phenyl sulfonyl, and R ₅And R ₆Be independently selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, C ₆～C ₁₂Aryl, acetyl group, and methyl;

Y wherein ₂Be selected from O, N, and S, and R ₇Be selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, and C ₆～C ₁₂Aryl;

X wherein ₁And X ₂Be independently selected from hydrogen and be selected from F, Cl, and the halogen of Br;

X wherein ₃And X ₄Be independently selected from hydrogen and be selected from F, C1, and the halogen of Br; And

Y wherein ₃Be selected from N, O, and S, and N, Y ₄(wherein R ' is selected from hydrogen, C for NR ' ₁～C ₆Alkyl), O, _S, and NH, and R ₈Be selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, C ₆～C ₁₂Aryl, and acetyl group.

2. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 1, wherein said additive compound is for being selected from bisphenol-A, and 2, the 5-dimethyl furan; the 2-acetyl furan, 2-acetyl group-5-methylfuran, 1-(phenyl sulfonyl) pyrroles, 2; the 3-benzofuran, 2-butyl benzofuran, benzo-thiophene, 2; 3-two chloro-1,4-naphthoquinones, 1,2-naphthoquinones; 2,3-two bromo-1,4-naphthoquinones; 3-bromo-1, the 2-naphthoquinones, and glyoxal ethyline at least a.

3. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 1, the basic consumption of wherein said additive compound counts 0.01～10% by the total weight of electrolyte.

4. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 3, the basic consumption of wherein said additive compound counts 0.01～5% by the total weight of electrolyte.

5. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 4, the basic consumption of wherein said additive compound counts 0.01～1% by the total weight of electrolyte.

6. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 5, the basic consumption of wherein said additive compound counts 0.01～0.5% by the total weight of electrolyte.

7. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 1, wherein said additive compound forms passivation layer on anodal surface.

8. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 1, wherein said lithium salts is for being selected from LiPF ₆, LiBF ₄, LiSbF ₆, LiAsF ₆, LiClO ₄, LiCF ₃SO ₃, Li (CF ₃SO ₂) ₂N, LiC ₄F ₉SO ₃, LiSbF ₆, LiAlO ₄, LiAlCl ₄, LiN (C _xF _2x+1SO ₂) (C _yF _2y+1SO ₂) (x and y are natural number in the formula), LiCl, and LiI at least a.

9. the nonaqueous electrolytic solution of lithium secondary battery according to Claim 8, wherein said lithium salts use with the concentration of 0.6～2.0M basically.

10. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 1, wherein said non-aqueous organic solvent is for being selected from carbonic ester, ester, ether, and at least a in the ketone.

11. nonaqueous electrolytic solution according to the lithium secondary battery of claim 10, wherein said carbonic ester is selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), carbonic acid first propyl ester (MPC), ethyl propyl carbonic acid ester (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).

12. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 10, wherein said carbonic ester is the mixed solvent of cyclic carbonate and linear carbonate.

13. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 1, wherein said organic solvent comprises the mixed solvent of carbonate solvent and aromatic solvent.

14. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 13, wherein said aromatic solvent is the compound of following formula (7):

R wherein ₉Be selected from halogen, and C ₁～C ₁₀Alkyl, and n is 1～6 integer.

15. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 12, wherein said aromatic solvent is for being selected from benzene, fluorobenzene, toluene, benzotrifluoride, dimethylbenzene, and composition thereof at least a.

16. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 12, the volumetric mixture ratio of wherein said carbonate solvent and described aromatic solvent is 1: 1～30: 1.

17. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 1, wherein this electrolyte also comprises organic sulfuryl compound.

18. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 17, wherein said organic sulfoxide based compound is shown in following formula (8):

R wherein ₁₀And R ₁₁Be independently selected from primary alkyl, secondary alkyl, tertiary alkyl, alkenyl, cycloalkyl aryl, and C ₁～C ₄Alkyl, C ₂～C ₄Alkenyl, C ₃～C ₆Cycloalkyl and C ₆～C ₁₄Aryl, perhaps R ₁₀And R ₁₁Link together into ring.

19. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 18, wherein said R ₁₀Or R ₁₁One of be essentially vinyl.

20. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 17, wherein said organic sulfoxide based compound uses with the amount of electrolyte total weight 0.01～5% basically.

21. the nonaqueous electrolytic solution of a lithium secondary battery comprises:

Lithium salts; Organic solvent; And at least a bisphenol-A that is selected from, 2, the 5-dimethyl furan, 2-butyl benzofuran, benzo-thiophene, and 2,3-two chloro-1, the additive compound of 4-naphthoquinones.

22. a lithium secondary battery comprises:

Positive pole, it comprises reversibly the material that embeds/deviate from lithium ion, and reversibly forms one of material of lithium-containing compound, as positive active material;

Negative pole, it comprises the lithium metal, contains lithium alloy, and reversibly embeds/deviate from a kind of in the material of lithium ion; And

Nonaqueous electrolytic solution, wherein this nonaqueous electrolytic solution comprises:

Lithium salts;

Organic solvent; And

At least a additive compound, it is selected from the compound shown in the following formula (1) to (6):

R wherein ₁And R ₂Be independently selected from hydroxyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, the C that halogen replaces ₁～C ₆Alkoxyl, C ₁～C ₄Alkyl, C ₂～C ₄Alkenyl, C ₆～C ₁₄Aryl, and C ₃～C ₆Cycloalkyl, the alkyl that halogen replaces, alkenyl, aryl, and the C of cycloalkyl and halogen replacement ₂～C ₆Alkenyl, and R ₃And R ₄Be independently selected from C ₁～C ₆Alkyl, C ₆～C ₁₂Aryl, and methyl;

Y wherein ₁Be selected from O, (wherein R is selected from hydrogen to NR, C ₁～C ₆Alkyl, C ₆～C ₁₂Aryl, the 1-phenyl sulfonyl), and S, and R ₅And R ₆Be independently selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, C ₆～C ₁₂Aryl, acetyl group, and methyl;

Y wherein ₂Be selected from O, N, and S, and R ₇Be selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, and C ₆～C ₁₂Aryl;

X wherein ₁And X ₂Be independently selected from hydrogen and be selected from F, Cl, and the halogen of Br;

X wherein ₃And X ₄Be independently selected from hydrogen and be selected from F, Cl, and _BrHalogen; And

Y wherein ₃Be selected from N, O, and S, Y ₄(wherein R ' is selected from hydrogen, C for NR ' ₁～C ₆Alkyl), O, S, and NH, and R ₈Be selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, C ₆～C ₁₂Aryl, and acetyl group.

23. according to the lithium secondary battery of claim 22, wherein said positive pole comprises a kind of in lithium-Ni-based and the lithium-nickel-manganese base oxide.

24. according to the lithium secondary battery of claim 22, wherein said electrolyte comprises and is selected from bisphenol-A, 2, and the 5-dimethyl furan; the 2-acetyl furan, 2-acetyl group-5-methylfuran, 1-(phenyl sulfonyl) pyrroles, 2; the 3-benzofuran, 2-butyl benzofuran, benzo-thiophene, 2; 3-two chloro-1,4-naphthoquinones, 1,2-naphthoquinones; 2,3-two bromo-1,4-naphthoquinones, 3-bromo-1; the 2-naphthoquinones, glyoxal ethyline, and composition thereof additive compound.

25. according to the lithium secondary battery of claim 22, wherein said electrolyte comprises the additive compound that is essentially electrolyte total weight 0.01～10% amount.

26. according to the lithium secondary battery of claim 22, wherein said electrolyte comprises the additive compound that is essentially electrolyte total weight 0.01～5% amount.

27. according to the lithium secondary battery of claim 22, wherein said electrolyte comprises and is selected from LiPF ₆, LiBF ₄, LiSbF ₆, LiAsF ₆, LiClO ₄, LiCF ₃SO ₃, Li (CF ₃SO ₂) ₂N, LiC ₄F ₉SO ₃, LiSbF ₆, LiAlO ₄, LiAlCl ₄, LiN (C _xF _2x+1SO ₂) (C _yF _2y+1SO ₂) (x and y are natural number in the formula), LiCl, and the lithium salts of LiI.

28. according to the lithium secondary battery of claim 22, wherein said electrolyte comprises and is selected from carbonic ester, ester, ether, and the non-aqueous organic solvent of ketone.

29. according to the lithium secondary battery of claim 22, wherein said electrolyte also comprises organic sulfuryl compound.

30. according to the lithium secondary battery of claim 29, wherein said organic sulfoxide based compound is shown in following formula (8):

R wherein ₁₀And R ₁₁Be independently selected from primary alkyl, secondary alkyl, tertiary alkyl, alkenyl, cycloalkyl aryl, C ₁～C ₄Alkyl, C ₂～C ₄Alkenyl, C ₃～C ₆Cycloalkyl and C ₆～C ₁₄Aryl, perhaps R ₁₀With R ₁₁Combine into ring.

31. according to the lithium secondary battery of claim 30, wherein said R ₁₀Or R ₁₁One of be mainly vinyl.

32. according to the lithium secondary battery of claim 29, wherein said organic sulfoxide based compound uses with the amount of electrolyte total weight 0.01～5%.

33. according to the lithium secondary battery of claim 22, wherein said lithium secondary battery comprises lithium ion battery or lithium polymer battery.

34. according to the lithium secondary battery of claim 22, wherein said lithium secondary battery comprise have non-aqueous organic solvent nonaqueous electrolytic solution, described nonaqueous solvents is for being selected from carbonic ester, ester, ether, and at least a in the ketone.

35. lithium secondary battery according to claim 34, wherein said carbonic ester is selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), carbonic acid first propyl ester (MPC), ethyl propyl carbonic acid ester (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).

36. according to the lithium secondary battery of claim 34, wherein said carbonic ester is the mixed solvent of cyclic carbonate and linear carbonate.

37. according to the lithium secondary battery of claim 22, wherein said organic solvent comprises the mixed solvent of carbonate solvent and aromatic solvent.

38. according to the lithium secondary battery of claim 37, wherein said aromatic solvent is the compound of following formula (7):

R wherein ₉Be selected from halogen, and C ₁～C ₁₀Alkyl, and n is 1～6 integer.

39. the nonaqueous electrolytic solution of a lithium secondary battery comprises:

Lithium salts;

Organic solvent; And

At least a additive compound, it is selected from the compound shown in the following formula (1) to (6):

R wherein ₁And R ₂Be independently selected from hydroxyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, the C that halogen replaces ₁～C ₆Alkoxyl, C ₁～C ₄Alkyl, C ₂～C ₄Alkenyl, C ₆～C ₁₄Aryl, C ₃～C ₆Cycloalkyl, the C that halogen replaces ₂～C ₆Alkenyl, the alkyl that halogen replaces, alkenyl, aryl, and cycloalkyl, and R ₃And R ₄Be independently selected from C ₁～C ₆Alkyl, C ₆～C ₁₂Aryl, and methyl;

Y wherein ₁Be selected from O, (wherein R is selected from hydrogen to NR, C ₁～C ₆Alkyl, C ₆～C ₁₂Aryl, and 1-phenyl sulfonyl), and S, and R ₅And R ₆Be independently selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, C ₆～C ₁₂Aryl, acetyl group, and methyl;

Y wherein ₂Be selected from O, N, and S, and R ₇Be selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, and C ₆～C ₁₂Aryl;

X wherein ₁And X ₂Be independently selected from hydrogen and be selected from F, Cl, and the halogen of Br;

X wherein ₃And X ₄Be independently selected from hydrogen and be selected from F, Cl, and the halogen of Br; And

Y wherein ₃Be selected from N, O, and S, and N, Y ₄(wherein R ' is selected from hydrogen, C for NR ' ₁～C ₆Alkyl), O, S, and NH, and R ₈Be selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, C ₆～C ₁₂Aryl, and acetyl group; And

Organic sulfoxide based compound shown in the following formula (8):

R wherein ₁₀And R ₁₁Be independently selected from primary alkyl, secondary alkyl, tertiary alkyl, alkenyl, cycloalkyl aryl, C ₁～C ₄Alkyl, C ₂～C ₄Alkenyl, C ₃～C ₆Cycloalkyl and C ₆～C ₁₄Aryl, perhaps R ₁₀With R ₁₁Combine into ring.

40. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 39, wherein said R ₁₀Or R ₁₁One of be essentially vinyl.

41. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 39, the volumetric mixture ratio of wherein said carbonate solvent and described aromatic solvent is essentially 1: 1～and 30: 1.

42. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 39, wherein said R ₁And R ₂Be independently selected from C ₁～C ₄Alkyl, C ₂～C ₄Alkenyl, C ₆～C ₁₄Aryl, and C ₃～C ₆Cycloalkyl.

43. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 39, wherein said R ₁And R ₂Be independently selected from the alkyl that halogen replaces, alkenyl, aryl, and cycloalkyl.

44. according to the nonaqueous electrolytic solution of the lithium secondary battery of claim 39, wherein said organic sulfoxide based compound is selected from vinyl sulfone, the methyl sulfone, the methyl ethylene sulfone, the ethyl vinyl sulfone, phenylsulfone, phenyl vinyl sulfone, the chlorphenyl vinyl sulfone, the fluorophenyl vinyl sulfone, benzyl sulfone, tetramethylene sulfone, butadiene sulfone, and composition thereof.

45. a lithium secondary battery comprises:

Positive pole, it comprises reversibly the material that embeds/deviate from lithium ion, and reversibly forms one of material of lithium-containing compound, as positive active material;

Negative pole, it comprises the lithium metal, contains lithium alloy, and reversibly embeds/deviate from a kind of in the material of lithium ion; And

Nonaqueous electrolytic solution, wherein this nonaqueous electrolytic solution comprises:

Lithium salts;

Organic solvent; And

At least a additive compound, it is selected from the compound shown in the following formula (1) to (6):

R wherein ₁And R ₂Be independently selected from hydroxyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, the C that halogen replaces ₁～C ₆Alkoxyl, C ₁～C ₄Alkyl, C ₂～C ₄Alkenyl, C ₆～C ₁₄Aryl, and C ₃～C ₆Cycloalkyl, the alkyl that halogen replaces, alkenyl, aryl, and the C of cycloalkyl and halogen replacement ₂～C ₆Alkenyl, and R ₃And R ₄Be independently selected from C ₁～C ₆Alkyl, C ₆～C ₁₂Aryl, and methyl;

Y wherein ₁Be selected from O, (wherein R is selected from hydrogen to NR, C ₁～C ₆Alkyl, C ₆～C ₁₂Aryl, the 1-phenyl sulfonyl), and S, and R ₅And R ₆Be independently selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, C ₆～C ₁₂Aryl, acetyl group, and methyl;

Y wherein ₂Be selected from O, N, and S, and R ₇Be selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, and C ₆～C ₁₂Aryl;

X wherein ₁And X ₂Be independently selected from hydrogen and be selected from F, Cl, and the halogen of Br;

X wherein ₃And X ₄Be independently selected from hydrogen and be selected from F, Cl, and the halogen of Br; And

Y wherein ₃Be selected from N, O, and S, Y ₄(wherein R ' is selected from hydrogen, C for NR ' ₁～C ₆Alkyl), O, S, and NH, and R ₈Be selected from hydrogen, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl, C ₂～C ₆Alkenyl, C ₆～C ₁₂Aryl, and acetyl group; And

Organic sulfoxide based compound shown in the following formula (8):

R wherein ₁₀And R ₁₁Be independently selected from primary alkyl, secondary alkyl, tertiary alkyl, alkenyl, cycloalkyl aryl, C ₁～C ₄Alkyl, C ₂～C ₄Alkenyl, C ₃～C ₆Cycloalkyl and C ₆～C ₁₄Aryl, perhaps R ₁₀And R ₁₁Combine into ring.

46. according to the lithium secondary battery of claim 45, wherein said R ₁₀Or R ₁₁One of be essentially vinyl.

47. according to the lithium secondary battery of claim 45, wherein said R ₁₀And R ₁₁Be independently selected from alkyl, alkenyl, cycloalkyl and aryl that halogen replaces.

48. according to the lithium secondary battery of claim 45, wherein said organic sulfoxide based compound is selected from vinyl sulfone, the methyl sulfone, the methyl ethylene sulfone, the ethyl vinyl sulfone, phenylsulfone, phenyl vinyl sulfone, the chlorphenyl vinyl sulfone, the fluorophenyl vinyl sulfone, benzyl sulfone, tetramethylene sulfone, butadiene sulfone, and composition thereof.

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